That's waste that might go to a landfill, an incinerator or a treatment plant.

But many businesses are finding they can use their waste to make something valuable.

Dairy farmers use manure to make electricity. Yogurt and cheese-makers use liquid waste to fuel boilers.

It's a growing field, popularly known as "closing the loop," according to DeWitt engineering firm O'Brien & Gere. Companies trying to maximize efficiency are finding value in the same stuff that used to be nothing more than a disposal problem.

At Morrisville State College, the manure from about 250 cows saves the college about $60,000 a year. The college has a methane digester, which separates methane gas from cow manure and converts it into enough electricity to take care of 90 to 95 percent of the dairy complex's needs.

After the manure is processed in the digester, it is spread on the fields with improved nutrients for the soil, said Ben Ballard, a Morrisville assistant professor with a doctorate in renewable energy. Unprocessed manure poses problems with odor and contaminated runoff.

"It's better all around," Ballard said of the digester. "It's a pretty simple system, and it's better in terms of odor, pathogens and nutrients."

O'Brien & Gere has seen an increase in clients looking for ways to improve energy efficiency. Often that involves making energy out of waste products. O'Brien & Gere Senior Vice President Tim Barry and Vice President Kevin Bryant explained how they help companies do that.

The firm uses technology developed by Ecovation Inc., a corporation based near Rochester, to help companies harness the potential of their byproducts. O'Brien & Gere has built and installed systems to convert wine, cheese and yogurt byproducts into biogas that in turn is used to make steam and electricity.

Kraft Foods uses the process in its cream cheese processing plant in Lowville, Lewis County, and in its cheese plant in Campbell, Steuben County. At the Hood dairy plant in Oneida, biogas is sent to a cogeneration plant, where it is made into electricity.

Another notable project is the planned Riverview Business Park, in Volney. The project starts with Northeast Biofuels, a nearly complete ethanol plant, which will use its byproducts in a variety of ways.

Northeast Biofuels will process corn to make ethanol, which is blended with gasoline to increase octane and reduce emissions. The plant will use three of its major byproducts to fuel other processes.

The "distiller's grain" that remains after the corn is fermented will go to farmers to feed cattle and other animals. The carbon dioxide created will be captured and used in bottling operations for carbonated beverages. The corn oil byproduct will be used to make biodiesel, another fuel that can be used alone or mixed with petroleum diesel to run vehicles.

Eventually, Riverview owners Eric Will II, of Pompey, and Thomas Denney, of Cazenovia, hope to attract businesses that will supply one another with byproducts each can use. O'Brien & Gere would supply the systems that convert the byproducts into usable forms.

For example, a wastewater treatment plant could be converted into an anaerobic digester to produce methane fuel from municipal sludge, farm manure or organic waste produced in the park. A power plant could use the methane to make steam. The steam could heat the facilities of another park tenant.

Water reuse is another way of closing the loop. O'Brien & Gere developed a technology called ARROW, short for advanced reject recovery of water. The system allows companies to recover and reuse water that would otherwise be washed down a drain and into a sewer system.

ARROW purifies water used primarily in chemical and pharmaceutical processes. It might allow water used in one part of a process to be used again as steam in another part. The system makes it possible for companies to reduce liquid discharge, sometimes to zero.

O'Brien & Gere has ARROW projects under way with clients in New York.

"We're finding all these efforts under the umbrella of sustainability," Barry said. "Our clients in the public and private sectors are looking for ways to manage their carbon footprint, closing down that loop is a part of it."